Internal combustion engine



June 1, 1937. c Q QTTQSON 2,082,078

INTERNAL COMBUSTION ENGI NE Filed July 15, 1935 4 Sheets-Sheet 1 -4-l--v z I 7 I z? I 'l I f, v e g g INVENTOR CZZI'Z g; fimswd,

7 ATTORNEY June 1, 1937. QTTOSON 2,082,078

INTERNAL COMBUSTION ENGI NE BY 7 ATTORNEY June 1, 1937. c. c. OTTOSON2,032,078

INTERNAL COMBUSTION ENGINE Filed July 15, 1935 4 SheetsSheet s 0 I? 3040 3? J; 11 ,y z; 17 S -L J/ 30 o"? f f /-3/ 47 INVENTOR darl 6'.fllios'ow,

BY $7,} ATTORNEY June 1,1931. c. c. OTTOSQN 7 2,082,078

' INTERNAL COMBUSTION ENGINE I Filed July 15, 1953 4 Sheets-Sheet 4 a nZ? N l/ 7////////fl INVENTOR 2116: 03710,

W ORNEY Patented June 1 1937 UNITED STATES amen PATENT OFFICE Thisinvention relates to improvements in internal combustion engines; andthe invention has reference, more particularly, to a novel constructionof low weight, high speed internal combustion engine of the four cycletype adapted to operate on either gasoline or on low grade fuels, suchas light furnace oils, light distillatesr etc. This invention has forits general object to provide a novel construction of four cycleinternal combustion engine having a two-step piston, comprising upperand lower sections respectively reciprocating. in corresponding upperand lower cylinder sections or chambers, together with a novel valvearrangement whereby air admission is controlled, and timed to the firingchamber during proper OYOIGSLOI piston movement is attained forscavengin'gand cooling effects and for producinga-combustible fuel'mixture of high eiiiciency.

.Other and more specific objects of this invention, not at this timemore particularly enumerated, will be understood from the followingdetailed description of the same.

An illustrative embodiment of-this invention is shown in theaccompanying drawings, in which:

Fig. 1 is a side elevation of an internal combustion engine according tothis invention, the

lower part of the crank-case and parts of the gear housing beingremoved; Fig. 2 is a transverse vertical section, taken on line 22 inFig. 1.

Figs. 3, 4, 5 and 6 are respectively diagrammatic or schematic viewsillustrating the piston and valve operation of the engine during theseveral cycles of piston 'movement.

Fig. 7 is a fragmentary transverse vertical section illustrating amodified form of piston air bypass valve and actuating means therefor.

Similar characters of reference are employed in the abovedescribedviews,ftoindicate corresponding parts.'

To simplify illustration the principles of this invention are shown inthe above described views as embodied in a single cylinder engine,butyitj will be understood that novel arrangements and constructions areequally applicable to engines of the multi-cylinder type;

Referring tosaiddrawings, the reference character Ill indicates thecylinderblock which is bored to provide an upper or firing chambersection II and a lower or air chamber section l2, the latter of enlargeddiameter comparative ,to the former. Suitably secured to the upper endof the cylinder block I is a cylinder head l3.

delivery oi. admitted air erably .of the poppet type. i-

Suitably secured to the lower end of the cylinder block III is a crankcasing I4, in which is iournaled a crank-shaft l5.

Connected with the cylinder block it for communication with the a"chamber section 12 is a valve housing l6, thesame having an exteriorlyopeningair admission port "through which "is admitted air forscavengingand cooling effects, and which, for purposes of distinction from otherair admission means, will referred to as the primary air port. At theinner end of said primary airport ll isprovided a valve seat 18 toreceivea primary air valve I 9, preferably of the poppet-type; i. e.spring-urged to a normally closed position; Also connected with thecylinder block ill for communication with the air chamber section I! isa valve, housing 20,'the same having an air admission port 2| throughwhich air is admitted I for fuel admixture purposes, and which, for pur-20 poses ofdistinction from said scavenging-"and cooling air admissionport i 1, will be hereinafter referred to as the secondary air port. Atthe inner end of said secondary air port 2i is provided a valve seat ,22to receive a secondary air valve 23, which is also preferably of thepoppet type, i. e. spring-urged to a normally closed position. Connectedwith. the outer end of said secondary air port 2| is an intake duct 24provided in the passage thereof with a manipulatable control or throttlevalve 25 for varying at will the volume of air admitted through thesecondary air port 2| upon opening of the valve 23 Connected with thecylinder head l3 for .communication with the firing chamber section. IIis a valve housing 26, the same having an outwardly opening exhaust port21. At the inner end of said-exhaust port 21 is provided a valve seat 28to receive an exhaust valve 29-, which-is prefspring-urged tonormallyclosed position. Arranged for reciprocation within the. cylinderblock lilis a-two-step piston, comprising an up per section 30 movablein the firing chamber =4 section ll and a lower section 3| movable inthe i air chamber-section l2. The upper section-30 and lower section ofthe piston are suitably constructed and assembled together so as toprovid'e intermediate air by, -pas s or transierpas--.- sage 32 which,at its lower a with the interior of said air chamber section l2 end,communicates of the cylinder block -l0 ,'and which, at its upper end,-communicates with an air delivery port 33 in the top of the upper pistonsection leading into I be hereinafter 10 r the firing chamber section IIof the cylinder block. At the discharge side of said air delivery port33 is a valve seat 34 to receive an air delivery valve 33, which ispreferably of the poppet type, i. e. spring-urged to normally closedposition. The stem 33 of said air-delivery valve 33 is slidably mountedin a guide bushing 31 to project into the hollow open lower end portion33 of the piston so as to terminate above the location of a wrist-pin 33diametrically extending across the piston.

The piston is operatively connected with the crank portion l3 of thecrankshaft l3 by a connecting rod or pitman 43, the upper end or knuckle43' of which is pivotally engaged with the piston wrist-pin 33. Meansare provided for efl'ecting opening movement of the air deliveryvalve'33 during up-rnoving cycles of the piston operation. In one form,as shown more particularly in Fig. 2 of the drawings, this meanscomprises a lift-lever 4| which is pivotally connected to the interiorside wall of the piston to extend transversely beneath and in engagementwith the lower end of the air delivery valve stem 33. Connected with theknuckle 43' of the connecting rod or pitman 43 is arocker-arm 42 adaptedto be oscillated by certain movements of the latter to impartup-swinging movement to said lift-lever 4| for transmission to saidvalve stem 33 whereby the air delivery valve 33 is caused to open duringup-moving cycles of the piston operation.

Suitably journaled in bearing, supports 43, as provided for example inconnection with .the crank-casing I4, is a camshaft 44 adapted to bedriven from the crank-shaft "in properly timed relation by transmissiongearing 43. Fixed on said cam-shaft 44 is aprimary air valve actuatingcam 43, a secondary air valve actuating cam 41 and an exhaust valveactuating cam 43. Slidable in a-guide 43 is a lift-piece 33 having afoot portion 3| engageable by the primary air valve actuating cam 43;said lift-piece 33 is suitably coupled with the stem 32 of said primaryair valve i3. Slidable in a similar guide 33 is a liftpiece 34 having afoot portion 33 engageable by the secondary air. valve actuating cam 41;said lift-piece 34 is suitably coupled with the stem 33 of saidsecondary air valve 23.

The exhaust valve 23 is provided with an outwardly extending exteriorlyprojecting stem 31, slidable in a guide bushing 33 afllxed through awall of the valve housing 23. Pivotally mounted in connection with afulcrum post 33 secured exteriorly to the valve housing 23 is arocker-arm 30, one branch of which operatively engages the exhaust valvestem 31. Slidable in a guide 3| is a lift-piece 32 having a foot portion33 engageable by the exhaust valve actuating cam 43. Said liftpiece 32is connected with the branch of said rocker-arm 33 by means of alink-rod 34.

Connected with the cylinder head 13 to communicate with the firingchamber section II of the cylinder block I3 is a liquid fuel injector'orspray nozzle 33. Timed delivery of liquid fuel into the firing chambersection II through said injector or spray nozzle 33 is effected by anysuitable form of fuel pump mechanism. Preferably the fuel pump mechanismincludes a regulator means for more or less automatically regulating thequantum of liquid fuel charge delivered into the firing chamber sectionin accordance with varying conditions of engine operation. Illustrativeof one arrangement of fuel pump means and regulator therefor, a housing33 is suitably mounted on a supporting bracket 31 connected aoaaove withthe upper section of the crank-casing I4. Journaled in connection withthis housing is a shaft 33 adapted to be driven from the crankshaft l3,in proper timed relation thereto, by transmission gearing 33. Aflixedupon and rotated by the shaft 33 is a fuel pump actuating cam 10.Connected with said housing, is a fuel pump casing II having a pump bore'I2 in which is slidably movable a spring retracted pump plunger I3having an external thrust head 14 to cooperate with said actuating camI3. At the intake end of said pump bore I2 is coupling means I3 and aninwardly opening check-valve I3. A liquid fuel supply conduit 'I'I,leading from any suitable fuel storage reservoir or like source ofsupply, is connected with said coupling means 13 and through saidinwardly opening check-valve 13 in communication with the pump bore I2.Said pump casing II is provided with a fuel discharge port I3,cooperative with which is an outwardly opening check-valve I9. Coupledin communication with said discharge port 13, by any suitable couplingmeans, is a fuel delivery conduit 30 which extends to and is coupledwith the injector or spray nozzle 33 so as to deliver the fuel chargesthereto. Illustrative of the pump regulator means, there is provided inconnection with the housing 33 a diaphragm casing 8i, the interior ofwhich is divided a flexible diaphragm 32 into a lower atmosphericpressure chamber 33 beneath the diaphragm, the wall of which is providedwith a port 34 open to the atmosphere, and an upper vacuum or lowpressure chamber'33 above the diaphragm, which is connected, through aconduit 33, in communication with the air intake duct 24 at a pointintermediate the intake side of the secondary air valve 23 and themanipulatable' control or throt tle valve 23 for purposes to besubsequently set forth. Connected with the center of said diaphragm 32is a plunger rod comprising an upper section 31 slidably movable in aguide bushing 33 which is carried by an adjusting member 33 threaded toa neck 93 of the diaphragm casing 3|. I

A pressure spring 9| is arranged about the upper section 31 of saidplunger rod'between the diaphragm 32 and said adjusting member, and isadapted to exert a tenslonal downward thrust upon the diaphragm andplunger rod. Said plunger rod further comprises a lower section 32slidably movable in a guideway 33 provided in connection with the wallof the housing 33, whereby the lower end of said plunger rod section 92enters the interior of said housing 33. Pivotally connected with theextremity of said plunger rod section 192 is an adjusting wedge 34 whichlies intermediate the pump actuating cam 10 and pump plunger thrust headI4.

In operation, the engine is designed to effect a four stroke cycle ofpiston movement, which may be briefly characterized as follows:- Thefirst stroke constitutes the power and scavenging air intake pistonstroke; the second stroke constitutes the exhaust and scavenging andcooling air stroke; the third stroke constitutes, the vacuum, fuelinjection and measured fuel air constituent stroke; and the fourthstroke constitutes the compression and fuel and air mixing stroke.

The operations during each pistonstroke, and the working of the enginevalve system in accordance therewith, will now be successivelydescribed, and will be best understood by reference to the schematicviews shown in Figs. 3 to Get the drawings.

First stroke-Assuming that the firing chamber section II is filled witha combustible fuel mixture, which has been compressed preparatory tofiring, the upper and lower piston sections 30 and 3| are disposed attop positions in their,

respective cylinder sections 'II and I2, during which piston positionthe measured or secondary air valve 23, the exhaust valve 29 and airdelivery valve 35 are closed, with the primary air valve l9 beginning toopen (see Fig. 3). Under these conditions the compressed fuel charge isfired by any suitable ignition means, such e. g. as the commonly usedelectrical ignition spark plug 95. Upon firing of the charge, the pistonis driven downward on its power stroke, the respective piston sections30 and 3| descending respectively in the cylinder chambers II and I2. Asthis piston movement takes place, the primary air valve I 9 is timed toopen, whereby descent of the piston section 3| draws .through the airadmission port I! and into the cylinder air chamber I2 a fullunrestricted volume of cool air. By the time'the piston completes itsdownward stroke and reaches bottom center position, the primary airvalve I9 closes again. 'It will thus be seen that. a cool airchargeistrapped in the cylinder air chamber I2 ready to be transferred throughthe transfer passages of the upper piston section 30 and air deliveryvalve 35 into the firing chamber I I during the next stroke of pistonmovement, and therein employed for scavenging and cooling effect as willhereafter appear. The capacity of the cylinder air chamber I2 is equalto and may be slightly greater than the upper piston displacementcapacity of the firing chamber I. It will be noted that on the downwardstroke of the piston, the

pitman 40 will swing to the right, and consequently the rocker-arm 42will swing downwardly and away from the lift-lever 4|, so that nomovement is imparted to the latter or to the air delive ery valve 35actuatable thereby and therefore said valve 35 remains closed.

Second stroke.-At the end of the downward movement or power stroke ofpiston operation, the cylinder firing chamber Ills filled with spent orburned gases resulting from combustion of the fuel mixture charge, andthe cylinder air chamber I2 is filled with a full or maximum charge ofcool air. As upward movement of the piston begins, the exhaust valve 29is timed to open, and as the pitman 40 swings to the left, therocker-arm 32 will swing upwardly against the lift-lever I so that, asthe piston moves upward, the lift-lever 3| will be upswung to therebylift the air delivery valve 35 and thereby open the air delivery port 33in the piston top during the rising movement of the piston. By virtue ofthe positions of their controlling actuating earns, the primary airvalve I3 and secondary air valve 23 remain closedduring the secondstroke of piston movement. With the exhaust valve 29 and air deliveryvalve 35 opened, as the piston rises, its lower section 3| movingupwardly in the cylinder air chamber I2,

drives the air previously indrawn and trapped therein, upwardly throughthe by-pass or transfer passages 32 of the upper piston section 3|! andthrough the open port 33 of the latter into the cylinder firing chamberThe cool air is thus caused to sweep through the cylinder firing chamberso as to'both drive out through the open exhaust valve 29 the spent orburned gases, while at the same time functioning to reducethe'temperature of the piston and the cylinder walls. It will thus beobvious that a very thorough scavenging of the firing chamber iseffected, and that the heat resulting from combustion of the fuelmixture charge is quickly and efilciently dissipated.

Third stroke.-At the end of the upward movement or scavenging stroke ofpiston operation, the piston sections 33-3I arrive at top center oftheir strokes in the respective cylinder chambers I I and I2, and againare ready for descent. By the time the pistons are thus positioned, thevalve control mechanism has operated to close the exhaust valve 29 andthe piston air delivery valve 35, while the primary air valve I3 remainsclosed. As the piston starts downward, the secondary air valve 23 istimed to open. The downward movement of the upper piston section causesthe same to produce a very low pressure (or vacuum) in the cylinderfiring chamber II, which reaches a maximum by the time the pistonarrives at bottom center. During the latter part of this downward pistonstroke, the injection of liquid fuel through the injector or spraynozzle 55 takes place; the fuel being delivered by the forcing stroke ofthe pump plunger 13 under the action of the cam I0,

which is timed to operatively engage the pump plunger during thisperiod. The downward movement of the lower piston section 3| in thecylinder air chamber l2 during this downward piston stroke, draws intosaid cylinder air chamber I2 a measured charge of air to be utilized asa constituent of the ultimate fuel mixture. The volume of this fuelmixture air constituent is subject to variation by manipulation of thethrottle valve 25; a maximum volume being attained at full openthrottle, which may be decreased in proportion to degree of throttleclosing down to a minimum volume when the throttle is closed.

Fourth stroke.Before the piston passes bottom center position, the airvalve 23 closes, and as the piston passes bottom center position (thevalves I9, 23 and 29 being and remaining closed) the pitman 40 swings tothe left and again carries the rocker-arm 42 into up-swinglng engagementwith the lift-lever II, so that as the piston moves upward, saidlift-lever will raise and open the air delivery valve 35. The rising ofthe lower piston section 3| in the cylinder air chamber I2 drives themeasured volume of air indrawn and trapped therein upwardly through theby-pass or transfer passages 32 of theupper piston section 30 andthrough the open port 33 into the cylinder firing chamber wherein thethus delivered measured volume of air is mixed with the previouslyentered'liquid fuel constituent to form the ultimate charge ofcombustible fuel mixture, which is at the same time compressedpreparatory to firing by the rising of the upper piston section 30 inthe firing chamber II. By the time the piston reaches top centerposition, the air delivery valve 35 again. closes, compression of thefuel mixture is completed, and repetition of the four strokes of thecycle of operation ensues. As the measured volume of air is deliveredinto the firing chamber II a high degree of turbulence will be induced,due to the difference in pressure in the upper and lower cylinderchambers. This turbulence will be further augmented by the upwardmovement of the lower piston section 3|, and consequently a verythorough intermixing of air and fuel constituents will result. About thetime the pistons have reached approximately halfway on their upwardstroke, or when an atmospheric equilibrium has been established in bothcylinder chambers, compression of the fuel mixture charge begins.

By manipulating the throttle 25 the volume. of air to serve as a fuelmixture constituent may be varied, and the fuel pump regulator will beactuated to effect a proportionate variation of the quantum of liquidfuel delivered by the pump.

, This latter efiect is obtained as follows: With the throttle 25 fullopen, there is a minimum of restriction to air admission into andthrough the intake duct 24 under the downward induction stroke of thelower piston section 3|, which occurs during the third cycle, andconsequently the pressure within low pressure chamber 85 above thediaphragm of the pump regulator is substantially thatof the atmosphereand therefore equal to the pressure in chamber 89 below the diaphragm.Under these conditions, the spring 9! exerts a downward thrust upon theplunger rod 81-92, which lowers the adjusting wedge 94 so that itsmaximum effective thickness is interposed between the pump plungerthrust head 14 and the actuating cam 10, and consequently the fulleffective stroke of the latter is exerted upon the pump plunger 13 tocause delivery of a maximum charge of liquid fuel through the conduit 90to the injector or spray nozzle 65. When, however, the throttle 25 ismoved toward closed position, the resultant restriction upon airadmission into and through the'intake duct 24 under the induction strokeof the lower piston section 3|, tends to reduce pressure in the lowpressure chamber 85 through the communicating conduit 85, andconsequently the unbalancing of pressure conditions upon opposite sidesof the diaphragm 92, with high or atmospheric pressure effective uponthe under side of the latter, tends to raise the diaphragm and plunger8192 against the tension of spring 9|. This upward movement of theplunger 81-92 withdraws the adjusting wedge 94 so that a portion ofreduced thickness is interposed between the pump plunger thrust head I4and the actuating cam 10. As a consequence of this there is set up lostmotion between the cam and the pump plunger which reduces the effectivestroke of the latter, and thereby reduces the volume of liquid fueldelivered through the conduit to the injector or spray nozzle 55. Itwill thus be understood that the volume of fuel mixture is capable ofbeing automatically varied, accordingly as desirable under varyingengine operating conditions, by manipulating the throttle 25 which iseffective both to reduce the volume of air and liquid fuel constituentsof the ultimate fuel mixture charge delivered at any given time to thecylinder firing chamber.

From the above description it will be under-- stood, that a novelinternal combustion engine is provided, which operates on a four cycleprinciple, so as to use an internal flux of cool airfor both scavengingand engine cooling effects, and which at the same time ,is adapted toprovide an effective mode of operation as to fuel charge formation,control and compression, which is adaptableto almost anytype of fuelmixture, but which is especially advantageous in connection with fuelsof the heavier grades.

Referring now to Fig. 7 of the drawings, there is shown therein amodified form of mechanism for actuating the piston air delivery valve35. In this modified arrangement, instead of the pivoted lift-lever 4|androcker-arm 42 carried by the pitman 49, there is mounted within theinterior of the lower piston section 3| a vertically movable slottedcross-head having an upwardly extending yoke 91, which straddles thepitman knuckle 40', and the sides of which are slotted as at 98, tostraddle the wrist-pin 39. The upper end of this yoke 91 bears on thelower end of the stem 36 of the delivery valve 35. Said cross-head 96 isprovided at its lower margins with lift-cam members 99. Mounted on thepitman 40, below the cross-head 96 are rollers I00 which operativelyengage said lift-cam members during certain phases of the pitmanoscillation, viz. when the pitman 40 swings to the left, the rollers I00operatively move toward and engage the lift-cam members 99 to impart arising movement to the cross-head 96, which is in turn transmitted tothe air delivery valve stem 36 thereby lifting and opening the valve 35relative to the port 33 in the top of the upper piston section. Theseoperations occur during the second and fourth strokes of the cycleduring upward movement of the piston. During the first and third strokesof the cycle of piston movement, which accord with descending motion ofthe piston, the pitman oscillates to the right, so that the rollers I00are carried'away from the lift-cam members and consequently no liftingmotion is imparted to the cross-head 96 and the air delivery valve 35remains closed during these cycles. In this modified arrangement, theupper and lower piston sections are shown as cast in an integral pistonstructure, suitably cored to provide the air bypass or transfer passages32 leading from the cylinder air chamber I2 to the port 33.

I am aware that various changes may be made in the above describedconstructions and many apparently widely different embodiments of thisinvention could be made without departing from the scope thereof asdefined in the following claims. It is therefore intended that allmatter contained in the above description or shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

I claim:

1. In an internal combustion engine of the four cycle type having acylinder formed to provide an upper firing chamber and a lower airchamber with means to deliver a fuel charge to said firing chamber and atwo step piston reciprocable in said cylinder chambers, a timed airadmission means communicating with said air chamber adapted to admit airfor scavenging purposes, a second timed variable capacity air admissionmeans for admitting a measured quantity of air into said air chamber foruse as a fuel mixture constituent, said piston having a port at itsupper end to communicate with said firing chamber and passages leadingto said port from said air chamber, and a piston pitman actuated timedvalve means for said port.

municate with said firing chamber and passages leading to said port fromsaid air chamber, a timed valve means for saidport, a fuel pump meansfor injecting a combustible fuel constituent into said firing chamber,and means cooperative with said second air admission means .adapted toautomatically modify the fuelpump operation for maintaining aproportional relationship between the combustible fuel and airconstituents of the delivered fuel mixture.

3. In an internal combustion engine of the four cycle type having acylinder formed to provide an upper firing chamber and a lower airchamber with means to deliver a fuel charge to said firing chamber and atwo step. piston reciprocable in said cylinder chamber, an air intakemeans communicating with said air chamber, a valve to close said airintake means, timed means to open 1 said valve during the descendingpower stroke of said piston for the intake into said air chamber ofxairfor scavenging purposes, a second air intake means also communicatingwith said chamber, a second valve to close said second air intake means,regulatable means for governing the volume of air admissible throughsaid second air intake means, timed means to open said second valveduring the succeeding descending stroke of said piston for the intake ofa measured quantity of air for use as a'fuel mixture constituent, saidpiston having a port at its upper end to communicate with said firingchamber and passages leading to said port from said air chamber, and atimed valve means for said port.

4. In an internal combustion engine of the four cycle type having acylinder formed to provide an upper firing chamber and a lower airchamber and a two step piston reciprocable in said cylinder chambers, anair intake means communieating with said air chamber, a valve to closesaid air intake means, timed means to open said valve during thedescending power stroke of said piston for the intake .into saidair-chamber of air for scavenging purposes, a second variable capacityair intake means also communicating with said air chamber, a secondvalve to close said second air intake means, timed means to open saidsecond valve during the succeeding descending stroke of said piston forthe intake of a measured quantity of air for use as a fuelmixture'constituent, said piston having a port at its upper end tocommunicate with said firing chamber and passages leading to said portfrom said air chamber, a timed valve means for said port, a fuel pumpmeans for injecting a combustible fuel constituent into said firingchamber, and means cooperative with said' second air intake meansadapted to automatically modify the fuel pump operation for maintaininga proportional relationship between the combustible fuel and airconstituents of the delivered fuel mixture.

5. In an internal combustion engine of the four cycle type having acylinder formed, to provide an upper firing chamber and a lower airchamber and a two step piston reciprocable in said cylinder chambers, atimed air admission means communicating with said air' chamber adaptedto admit a maximum volume of air for scavenging purposes, a secondvariable "capacity timed air admission means for admitting a variablevolume of air into said air chamber for use as a fuel mixtureconstituent, said piston having a port at its upper end to communicatewith said firing chamber and passages leading to said port from said airchamber, a timed valve means for said port, a fuel pump having areciprocable plunger, means for reciprocating said plunger, and meansresponsive to variation of air volume through said second air admissionmeans for likewise varying the effective stroke of said fuel pumpplunger.

6. In an internal combustion engine of the four cycle typehaving acylinder formed to provide an upper firing chamber and a lower airchamber and a two-step piston reciprocable in said cylinder chambers, atimed variable capacity air admission for admitting a variable volume ofair into said air chamber for use as a fuel mixture .constituent, saidpiston having a port at its upper end to communicate with said firingchamber and passages leading to said port from said air chamber, a timedvalve means for said port, a fuel pump having a reciprocable plunger,

means for reciprocating said plunger, means responsive to variation ofair volume through said second air admission means for likewise varyingthe effective stroke of said fuel pump plunger, said latter meanscomprising an enclosed diaphragm having a chamber on one side open toatmosphere and a chamber on the opposite side in communication with saidsecond admission means, and means controlled by movements of saiddiaphragm for cooperation with said fuel pump plunger and itsreciprocating means for the purposes mentioned.

7. In an internal combustion engine, a timed variable capacity airadmission means for delivcry of a variable volume of air for use as afuel mixture-constituent for admission with fuel to the engine firingchamber, a fuel pump means for injecting a combustible fuel constituentinto said firing chamber, and means cooperative with said air admissionmeans adapted to automatically modify the fuel pump operation formaintaining a proportional relationship between the combustible fuel andair constituents of the delivered fuel mixture. s

8. In an internal combustion engine, a timed variable capacity airadmission means for delivery of a variable volume of air for use as afuel mixture constituent for admission with fuel to the engine firingchamber, a fuel pump having a reciprocable plunger, means forreciprocating said plunger, and means responsive to variation of airvolume admitted'through said air admission means for proportionallyvarying the effective stroke of said fuel pump plunger.

9. In an internal combustion engine, a timed variable capacity airadmission means for delivery of a variable volume of air for use as afuel mixture constituent for admission with fuel to the engine firingchamber, a fuel pump having a reciprocable plunger, means forreciprocating said plunger, means responsive to variation of air volumeadmitted through said air admission means for proportionally varying theeffective

